Medical device containing a multi-ply knit fabric

ABSTRACT

A medical device comprising a device that covers at least a portion of a patient&#39;s skin and has an inner surface designed to be in contact with the patient&#39;s skin. It contains a multi-ply knit fabric that contains a first knit ply and a second knit ply. The first knit ply contains a plurality of first yarns and forms the upper surface of the fabric. The second knit ply contains a plurality of polytetrafluoroethylene (PTFE) yarns which forms the lower surface of the fabric. The first and second ply are integrated through combined portions formed by interlacing first yarns among the PTFE yarns, interlacing PTFE yarns among the first yarns, and interlacing a plurality of third yarns among the first and the PTFE yarns. The multi-ply knit fabric also contains a composition comprising at least one silver ion-containing compound on at least the upper surface of the multi-ply knit fabric.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application62/741,305, filed on Oct. 4, 2018, which is herein incorporated byreference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention is directed towards wound dressing systems, moreparticularly to wound dressing systems containing multi-ply knit fabricswhere one of the plies contains polytetrafluoroethylene (PTFE) yarns.

BACKGROUND

In the medical field, and in the area of wound care particularly, it iswell-established that many factors, including the amount of moisturepresent at a wound site, affects how quickly a wound will heal.Generally speaking, having an excessive amount of moisture present at awound site, especially when combined with the warm environment providedby the body, leads to undesirable bacteria growth and production ofprotease enzymes in the wound. Such growth can cause further damage tohealthy cells and delay the healing process. However, insufficientmoisture at the wound site can cause eschar (scab) formation andscarring and may cause the wound care device, or medical dressing, toadhere to the wound. If the dressing adheres to the wound, subsequentremoval of the dressing may cause undue discomfort to the patient aswell as disrupt newly granulated tissue. Infection of the wound may alsobe compounded when a medical dressing is removed, and portions of thedressing remain behind in the wound itself, particularly if the dressingis already colonized with pathogenic microbes. Thus, it is importantthat the dressing maintains its physical integrity when exposed tostress, such as during removal from the wound, in order to preventadditional complications and delays in healing.

It is desirable to have a dressing system that renasfer excess moistureas well as does not stick to the wound, is low friction, ishypoallergenic, inert, and optionally create a dressing that is cool tothe patient's touch.

BRIEF SUMMARY OF THE INVENTION

A medical device comprising a device that covers at least a portion of apatient's skin. The device has an inner surface and an outer surface,where the inner surface is designed to be in contact with the patient'sskin. The inner surface of the device comprises a multi-ply knit fabrichaving an upper and lower surface and a length and width. The multi-plyknit fabric has an upper and lower surface and contains a first knit plyand a second knit ply. The first knit ply contains a plurality of firstyarns and forms the upper surface of the fabric. The second knit plycontains a plurality of polytetrafluoroethylene (PTFE) yarns, where thePTFE yarns have a density of about 2 to 2.3 g/cm³, a transmission in theIR region of 8-10 μm at least about 40%, and a thermal conductivity ofat least about 0.2 W/(m·K). The second knit ply forms the lower surfaceof the fabric. The first ply and the second ply are integrated throughcombined portions formed by at least one method selected from the groupconsisting of interlacing first yarns among the PTFE yarns of the secondknit ply, interlacing PTFE yarns among the first yarns of the first knitply, and interlacing a plurality of third yarns among the first yarns ofthe first knit ply and the PTFE yarns of the second knit ply. Themulti-ply knit fabric also contains a composition comprising at leastone silver ion-containing compound on at least the upper surface of themulti-ply knit fabric.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of one embodiment of a medical devicecontaining a multi-ply knit fabric.

FIG. 1B is a cross-sectional illustration of one embodiment of amulti-ply knit fabric.

FIG. 2 is a is a photo-micrograph of a cross-section of the multi-plyknit fabric according to one embodiment of the invention.

FIG. 3 is a photomicrograph of the upper surface of the multi-ply knitfabric of FIG. 2 .

FIG. 4 is a photomicrograph of the lower surface of the multi-ply knitfabric of FIG. 2 .

FIG. 5 is a photomicrograph of some PTFE yarns in the knit fabric.

FIG. 6 is a knit diagram of the multi-ply knit fabric according to oneembodiment of the invention.

DETAILED DESCRIPTION

Referring now to FIG. 1A, there is shown an illustration of oneembodiment of the medical device 1000. In FIG. 1A, the medical device isa wrist case, but it can be any suitable medical device that is locatedon or adjacent a patient's skin. The medical device has an inner surface1000 b and an outer surface 1000 a. Then inner surface 1000 b isdesigned to be in contact with the patient's skin.

In one embodiment, the medical device is an immobilizing device that isused to immobilize a portion of the patient's body. A cast and splintare examples of this type of device. In another embodiment, the medicaldevice is compression device which is used to compress portions of thepatient's body. An elastic bandage would be an example of a compressiondevice. In another embodiment, the medical device is a decompressiondevice which may use suction or a vacuum to decompress a portion of thepatient's body.

The medical device 1000 has a multi-ply knit fabric layer 10 forming theinner surface 1000 b of the device 1000. The multi-ply knit fabric 10can be been in FIG. 1B.

The knit fabric 10 has an upper surface 10 a and a lower surface 10 b.When the fabric 10 is placed into the system, preferably the lowersurface 10 b would be facing the patient and upper surface 10 a would befacing away from the patient. The knit fabric 10 of FIG. 1B is showncontaining 2 plies; a first knit ply 100 and a second knit ply 200. Theknit fabric 10 is a unitary material that is formed together in aknitting machine with the two plies separated by a dashed line. Theplies 100 and 200 are not formed as discrete knit layers and then joinedtogether in a later operation. FIG. 2 is a photomicrograph of across-section of one embodiment of the multi-ply knit fabric 10. FIG. 3is a photomicrograph of the upper surface (first knit ply) of themulti-ply knit fabric of FIG. 2 and FIG. 4 is a photomicrograph of thelower surface (second knit ply) of the multi-ply knit fabric of FIG. 2 .

The multi-ply knit fabric 10 may be made by any suitable knittingmethod, including both warp knitting and weft (or circular) knitting.Circular knitting is preferred in some embodiments, as it tends to bemore cost efficient. The two plies may have the same knit constructionor different.

The first knit ply 100 comprising a plurality of first yarns and formsthe upper surface 10 a of the fabric 10. The first yarns in the firstknit ply 100 may be any suitable yarn. “Yarn”, in this application, asused herein includes a monofilament elongated body, a multifilamentelongated body, ribbon, strip, yarn, tape, fiber and the like. The firstknit ply 100 may contain one type of yarn or a plurality of any one orcombination of the above. The yarns may be of any suitable form such asspun staple yarn, monofilament, or multifilament, single component,bi-component, or multi-component, and have any suitable cross-sectionshape such as circular, multi-lobal, square or rectangular (tape), andoval. In one preferred embodiment, the first ply 100 containsmultifilament polyester yarns as these have been shown to have goodperformance at low cost.

The first knit ply may have any suitable knit pattern and be formed byany suitable yarns. The yarns in the first ply may be a single pluralityor type of yarn (e.g., the fabric can be formed solely from yarnscomprising a blend of cellulosic yarns and synthetic yarns, such aspolyamide yarns), or the textile can be formed from several pluralitiesor different types of yarns (e.g., the fabric can be formed from a firstplurality of yarns comprising cellulosic yarns and polyamide yarns and asecond plurality of yarns comprising an inherent flame resistant yarn).The yarns may be formed of (but are not limited to) cellulosic yarns(such as cotton, rayon, linen, jute, hemp, cellulose acetate, andcombinations, mixtures, or blends thereof), polyester yarns (e.g.,poly(ethylene terephthalate) yarns, poly(propylene terephthalate) (PET)yarns, poly(trimethylene terephthalate) yarns), poly(butyleneterephthalate) yarns, and blends thereof), polyamide yarns (e.g., nylon6 yarns, nylon 6,6 yarns, nylon 4,6 yarns, and nylon 12 yarns),polyvinyl alcohol yarns, an elastic polyester-polyurethane copolymer(SPANDEX®), flame-resistant meta-aramid (NOMEX®) and combinations,mixtures, or blends thereof.

The second knit ply 200 comprising a plurality ofpolytetrafluoroethylene (PTFE) yarns and forms the lower surface 10 b ofthe fabric 10. Preferably, if the fabric 10 is made into a garment, thesecond knit ply 200 faces the wearer and is preferably in direct contactwith the wearer's skin. The lower surface 10 b of the fabric 10 has asurface roughness of less than about 500 μm, preferably less than about200 μm. PTFE yarn could be of any denier or sizes. In one preferredembodiment, 220 denier PTFE is used and in another embodiment, 100denier PTFE yarn is used. However, depending on the desired weight (ozper sq. yd) and other properties, the denier of the PTFE yarn could besmaller or larger.

The PTFE yarns have a density of about 2 to 2.5 g/cm³, more preferablyabout 2.0 to 2.3 g/cm³, more preferably about 2.15 to 2.25 g/cm³.Typical textile yarns, such polyester, nylon or cotton have density lessthan 1.6 g/cm³. The PTFE yarns have a transmission in the IR region of8-10 μm at least about 40%, more preferably at least about 60%. In caseof polyester, it has C—O stretching frequency from 7.7-10 micron and C—Hbending from 7.8-14.5 micron, which leads to reduced transmission, 20%or less in the IR region of 8-10 micron. It has been shown that this 20%of less transmission in the IR region of 8-10 microns produces a fabricwith less active cooling. The PTFE yarns also have a thermalconductivity of at least about 0.2 W/(m·K), more preferably at leastabout 0.23 W/(m·K), more preferably at least about 0.25 W/(m·K).Polyester yarn has much lower thermal conductivity of ˜0.15 W/(m·K).Preferably, the PTFE yarns have a generally rectangular cross-sectionalshape.

When measuring aspect ratio, the cross-section of the yarn is measuredacross the entire width (even if the tape is folded onto itself). In oneembodiment, the PTFE yarns have a cross-section aspect ratio across theentire width of between about 20:1 to 100:1. Typical flat polyester hasthe aspect ratio of less than 5:1. Typical PTFE yarn is used in a foldedstate, meaning that there are fold lines running along the length of thetape yarns and portions of the yarn lay on other portions of the yarn(sometimes like an accordion) such as can be seen in FIG. 5 . If theaspect ratio is measured of the folded PTFE yarn, the aspect ratio wouldbe between about 10:1 to 2:1.

The first 100 and second 200 plies are integrated through combinedportions, this is preferably done at the time of knitting such that thefabric 10 is created as a multi-ply knit fabric, not as two separateknit fabrics that are then joined in a subsequent process step. Thisintegration may be from one of the following methods, or a combinationof the methods.

The first method is interlacing first yarns from the first ply among thePTFE yarns of the second knit ply, meaning that a portion of the firstyarns from the first ply leave the first ply, travel down into thesecond ply where they are interlaced with yarns within the second ply,and then travel back up to the first ply.

The second method is interlacing PTFE yarns from the second ply amongthe first yarns of the first knit ply, meaning that a portion of thePTFE yarns from the second ply leave the second ply, travel up into thefirst ply where they are interlaced with yarns within the first ply, andthen travel back down to the second ply to the first ply.

The third method is interlacing a plurality of third yarns among thefirst yarns of the first knit ply and the PTFE yarns of the second knitply. This means that a third yarn (which may be the same or differentyarn than the first yarns and/or PTFE) travels between the plies,interlacing with yarns from both plies and in essence, tying themtogether. Preferably, the third yarns comprise PTFE yarns.

In a preferred embodiment, the second method is used to interlace thefirst 100 and second 200 ply together. This method is preferred becauseof the lower complexity during the knitting process using the circularknitting.

In one embodiment, the multi-ply knit fabric is made using what isreferred to as a flat back mesh construction. In this construction, theyarns are evenly spaced on the flat side, while the yarns are not spacedevenly on the mesh side (PTFE side) (open). The knitting diagram forthis construction can be seen in FIG. 6 . Preferably, the second ply ismore open than the first ply, meaning that there are gaps in the secondply (so that when looking at the lower surface of the fabric 10, some ofthe first ply 100 can be seen through the gaps in the second ply 200.The mesh allows the moisture from the human skin to transport moreefficiently to the environment, while minimizing the materials use. PTFEis preferably used in the mesh side. In the mesh side, the gaps betweentwo yarns could be up to 0.5-1 mm.

Thickness of the both faces are almost equally distributed, whilecontents of different yarns are controlled by changing the gap betweenthe yarns in the mesh side. Tightness of the knitting is also controlledto achieve the total fabric thickness. Typical fabric thickness can bevaried from 0.25-0.8 mm.

In one embodiment, the fabric 10 contains a third knit layer.Preferably, this third knit layer is on the first ply (on the sideopposite to the second ply) or between the first and second plies. Whenthe fabric 10 contains a third ply, the second play preferably stillforms the lower surface 10 b of the fabric 10. The third layer may beknitted from any of the materials (or combinations of materials)disclosed as suitable materials for the first 100 or second 200 ply andis preferably knit as the same time and integral with the first andsecond plies.

It is preferred to have the amount of PTFE yarns in the fabric 10 (as awhole) be as low as possible due to the cost of the PTFE yarns inrelation to the other yarns in the fabric 10. In one embodiment, thefabric 10 comprises less than about 75% by weight PTFE yarns. In anotherembodiment, the fabric 10 comprises less than about 50% by weight PTFEyarns. In another embodiment, the fabric 10 comprises between about 5and 75% by weight PTFE yarns. It is believed to be most important toconcentrate the PTFE yarns on the lower surface 10 b of the fabric 10 tomaximize their cooling effect, the non-stick, and other desiredproperties. In one embodiment, the second knit ply comprises at leastabout 90% by weight PTFE yarns. In another embodiment, the lower surface10 b comprises at least about 90% by weight PTFE yarns.

The multi-ply knit fabric also preferably contains a compositioncomprising at least one silver ion-containing compound on at least theupper surface of the multi-ply knit fabric. In another embodiment, theknit fabric is dip coated to the composition so that all of the surfacesof the yarns within the knit fabric are exposed to the composition.Typically, the composition sticks very minimally to almost not at all tothe PTFE yarns.

The silver ion-containing compound is preferably selected from the groupconsisting of silver ion exchange materials (e.g. silver zirconiumphosphates, silver calcium phosphates and silver zeolites), silverparticles (e.g. silver metal, nanosilver, colloidal silver), silversalts (e.g. AgCl, Ag₂CO₃), silver glass, and mixtures thereof. Onepreferred silver ion-containing compound is an antimicrobial silversodium hydrogen zirconium phosphate available from Milliken & Company ofSpartanburg, S.C., sold under the tradename AlphaSan®. Other potentiallypreferred silver-containing antimicrobials suitable for useherein—including silver zeolites, such as a silver ion-loaded zeoliteavailable from Sinanen Co., Ltd. of Tokyo, Japan under the tradenameZeomic®, and silver glass, such as those available from Ishizuka GlassCo., Ltd. of Japan under the tradename Ionpure® may be utilized eitherin addition to, or as a substitute for, the preferred species listedabove. Other silver ion-containing materials may also be used. Variouscombinations of these silver-containing materials may be made ifadjustments to the silver release rate over time are desired.

Generally, the silver-based compound is added in an amount from about0.01% to about 60% by total weight of the particular finish composition;more preferably, from about 0.05% to about 40%; and most preferably,from about 0.1% to about 30%. The antimicrobial finish itself, includingany desired binders, wetting agents, odor absorbing agents, levelingagents, adherents, thickeners, and the like, is added to the substratein an amount of at least about 0.01% of the total device weight.

A binder material has been found useful in preventing the antimicrobialfrom flaking off the fabric and onto the wound. Preferably, thiscomponent is a polyurethane-based binding agent, although a wide varietyof cationic, anionic, and non-ionic binders may also be used, eitheralone or in combination. Preferably, the binding agent is biocompatiblesuch that is does not cause negative reactions in the wound. In essence,such binders provide durability by adhering the antimicrobial to thetarget substrate, such as fibers or fabrics, without negativelyaffecting the release of silver ions to the wound.

Total add-on levels of silver to the target substrate may be 20 ppm orhigher. More preferably, total add-on levels of silver may be 200 ppm orhigher. Although an upper boundary limit of silver add-on levels to thetarget substrate has not been determined, consideration of themanufacturing economics and the potential to irritate a sensitive woundsite suggests avoiding excessive silver levels.

Silver ion-containing compounds (such as AlphaSan®, Zeomic®, orIonpure®) may be admixed in an aqueous dispersion with a binder to forma bath into which the knit fabric is immersed. Other similar types ofcompounds that provide silver ions may also be utilized.

When specific polyurethane-based binder materials are utilized, theantimicrobial characteristics of the treated substrate are effectivewith regard to the amount of surface available silver that is releasedto kill bacteria, without altering the color of the treated substrate(that is, while substantially maintaining its original appearance).While it currently appears that the use of polyurethane-based binderresins are preferred due to their allowance of silver release andbio-neutral properties, in practice essentially any effective cationic,anionic, or non-ionic binder resin that is not toxic to the wound may beused.

An acceptable method of providing a durable antimicrobial silver-treatedfabric surface is the application of a silver ion-containing compoundand polyurethane-based binder resin from a bath mixture. This mixture ofantimicrobial compound and binder resin may be applied through anytechnique as is known in the art, including spraying, dipping, padding,foaming, printing, and the like. By using one or more of theseapplication techniques, a fabric may be treated with the antimicrobialcompound and binder resin on only one side of the fabric (e.g. the woundcontact surface of a wound care device), or it may be treated on bothsides of the fabric.

Preferably, the multi-ply knit fabric (as well as all of the otherlayers within the systems 500, 900) are sterilized. This sterilizationcan occur to each layer within the systems before assembly or after thesystems are assembled together. Any suitable sterilization method may beused that does not harm or otherwise interfere with the desiredproperties of the systems. For example, heat, irradiation, or chemicalsmay be used separately or in combination to sterilize the systems 500,900.

In one embodiment, the multi-ply knit fabric 10 and/or the systems 500,900 are non-electrically conductive. “Non-electrically conductive” isdefined as having a resistance in ohms per square inch of fabric ofgreater than about 10,000 ohms, preferably greater than about 100,000ohms and most preferably greater than about 1×10⁹ ohms, when measured inaccordance with AATCC Test Method 76-1978.

Test Methods

Weight of the fabric was measured using ASTM D 3776. Air permeabilitywas measured using ASTM D 737. MVTR was measured ASTM E 96-95: WaterVapor Transmission of Materials, modified procedure B; both Open JarMethod and with the Air Flow method. Q-Max is the measurement of themaximum heat loss that can occur when the skin touching objects or othermaterials. Larger Q-max, cooler the material, in this case fabric, tohuman touch. The Kawabata thermal tester (Thermolabo) is used to measurethe Q-max. Intrinsic thermal resistance, apparent intrinsic evaporativeresistance, and total heat loss are measured using a sweating guardedhot plate using ASTM F1868, Part C.

EXAMPLES

The table below summarizes the 13 examples. The PTFE yarn used waseither 220 den (Lenzing™ Profilen FG02 natural) and 100 den (Lenzing™Profilen FR110 natural). The polyester yarn used was a multi-filamentyarns in a 1 ply or 2 ply 70/72 construction. Examples 1-8 were knittedin flat back mesh construction as shown in FIG. 6 . Example 9 was a50/50 PTFE (220 den)/polyester interlock knit and example 10 was a 100%polyester interlock knit. Examples 1-10 were subjected to navy dispersedyeing process and tentering for testing and evaluation. Example 11 wasa commercially available fabric from ADIDAS™ called Climachil which is adouble knit, bi-ply. The outerply contains typical multifilament roundpolyester yarn and the inner ply contains multifilament flat polyesteryarns.

Polyester PTFE Ounces per square Yarn content yarn type yarn type yard(OSY) oz/yd² Ex. 1 69%/31% 1/70/72 220 den 5.7 PTFE/polyester Ex. 253%/47% 2/70/72 220 den 8.8 PTFE/polyester Ex. 3 36%/64% 2/70/72 100 den6.0 PTFE/polyester Ex. 4 54%/46% 1/70/72 100 den 3.7 PTFE/polyester Ex.5 77%/23% 1/70/72 220 den 5.5 PTFE/polyester Ex. 6 62%/38% 2/70/72 220den 7.8 PTFE/polyester Ex. 7 45%/55% 2/70/72 100 den 5.6 PTFE/polyesterEx. 8 63%/37% 1/70/72 100 den 3.3 PTFE/polyester Ex. 9 50%/50% 1/70/72220 den 6.8 PTFE/polyester Ex. 10 100% Polyester 1/70/72 — 4.9 and2/70/72 Ex. 11 See description — — 4.2 above

The examples were tested for air permeability, moisture vaportransmission rate (MVTR) (ASTM E 96-95: Water Vapor Transmission ofMaterials, modified procedure B; both Open Jar Method and with the AirFlow) (g/m²/24 hrs) and Q-max (watts/cm²) of back (skin side) and faceof the fabrics.

MVTR MVTR Q-max Q-max air perm (Open Jar) (Air Flow) (back) (face) (cfm)g/m²/24 hrs g/m²/24 hrs watts/cm² watts/cm² Ex. 1 320 882.37 6090 0.2130.114 Ex. 2 206 879.53 2.52 0.134 Ex. 3 235 862.51 0.187 0.128 Ex. 4 403876.70 0.167 0.113 Ex. 5 406 848.33 6169 0.214 0.108 Ex. 6 227 845.490.215 0.117 Ex. 7 270 913.58 5888 0.169 0.118 Ex. 8 466 842.65 0.1540.104 Ex. 9 127 868.19 2205 0.165 0.106 Ex. 10 140 811.44 2374 0.1220.118 Ex. 11 202 713.95 0.155 0.111

As one can see form the table above, examples containing PTFE yarn(Examples 1-9) has slightly higher MVTR (˜840-900 g/m²/24 hrs) than thepolyester examples (Examples 10-11) (˜700-800 g/m²/24 hrs). ComparingExamples 1, 5, and 7 (knitted with the flat back mesh construction asshown in FIG. 3 ) had much higher MVTR values in the military method,where there is airflow at the top of the jar compared to Examples 10 and13 (without the PTFE yarns). This indicates the moisture vaportransmission is induced by the airflow.

In terms of cooling effect, the higher the Q-max, cooler the fabricfeels to its touch. The Q-max measurement using Kawabata thermal tester(Thermo Labo) showed higher Q-max values on both sides of the fabric ofExamples 1-9 compared to Examples 10-11.

Apparent Intrinsic intrinsic Total Thermal evaporative Thermal Heatresistance resistance Resistance loss Thick- Sample (R_(cf)) (R_(ef))(I_(t)) (Qt) ness ID (Δ° C.)(m²)/W (ΔkPa)(m²)/W Clo W/m² mm Ex. 1 0.0040.00206 0.492 869.36 0.42 Ex. 2 0.006 0.00264 0.506 798.26 0.57 Ex. 30.007 0.00247 0.509 812.34 0.5 Ex. 4 0.007 0.00098 0.512 1008.92 0.35Ex. 5 0.004 0.00137 0.493 959.05 0.41 Ex. 6 0.006 0.00228 0.502 837.110.57 Ex. 7 0.006 0.0018 0.504 891.68 0.45 Ex. 8 0.004 0.00107 0.4911009.41 0.31 Ex. 9 0.01 0.00181 0.532 871.17 0.62 Ex. 10 0.009 0.002350.525 814.05 0.62

Total heat loss was measured using a large sweating guarded hot plate asper ASTM F1868 part C and data is summarized in the table above. Thismeasurement confirmed that intrinsic thermal resistance of PTFE yarnbased knits with flat back mesh construction fabric (Ex. 1-8) is lowercompared to all polyester fabrics (Ex. 10). The evaporative resistanceof PTFE containing knits (Ex. 1-8) are lower compared to the allpolyester knit (Ex. 10). Lower thermal resistance along with lowerevaporative together yielded fabrics with impressive up to 25%improvement in the total heat loss, comparing Ex. 1-8 with Ex. 10.

In conclusion, excellent Q-max, excellent thermal conductivity (lowerresistance), lower evaporative resistance, higher heat loss for PTFEbased flat back mesh knits (Examples 1-8). All these properties areimportant for active cooling application in textile.

Examples 11-13 compared to Example 1 explore peel strength adhesionbetween a knit fabric and pig skin. To test the examples, a 2″×4″ sampleof the knit fabric was placed on the dermis/hypodermis of pig skin withbovine serum and then 3 layers of gauze were placed on the knit layer.The samples were then dried for 16 hours at 37° C. Peel strength wasthen measured.

Adjusted Peel Peak Load Peak Load Energy Example Commercial nameDescription [lbf] [lbf] [in*lbf] Ex. 11 TRITEC ® silver polyester/nylon0.334 0.331 0.322 dressing bilayer knit available from Milliken & Co Ex.12 ASSIST ® silver polyester/nylon 0.236 0.232 0.283 dressing bilayerfabric available from with non-stick Milliken & Co backing Ex. 13 Finemesh Rayon/polyester 0.591 0.544 1.16 gauze (6 layers) nonwoven Ex. 169%/31% 0.043 0.005 0.02 PTFE/polyester

As one can see from the chart above, the peak load, adjusted peak load,and the peel strength of the commercial examples 11-13 weresignificantly higher than the example 1 meaning that example 1 peeledoff from the pig skin much easier than examples 11-13. Preferably, thepeel test (according to this testing method), is less than about 0.1in*lbf, more preferably less than 0.05 in*lbf.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the subject matter of this application (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The terms “comprising,” “having,”“including,” and “containing” are to be construed as open-ended terms(i.e., meaning “including, but not limited to,”) unless otherwise noted.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the subject matter of theapplication and does not pose a limitation on the scope of the subjectmatter unless otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element as essential to thepractice of the subject matter described herein.

Preferred embodiments of the subject matter of this application aredescribed herein, including the best mode known to the inventors forcarrying out the claimed subject matter. Variations of those preferredembodiments may become apparent to those of ordinary skill in the artupon reading the foregoing description. The inventors expect skilledartisans to employ such variations as appropriate, and the inventorsintend for the subject matter described herein to be practiced otherwisethan as specifically described herein. Accordingly, this disclosureincludes all modifications and equivalents of the subject matter recitedin the claims appended hereto as permitted by applicable law. Moreover,any combination of the above-described elements in all possiblevariations thereof is encompassed by the present disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A medical device comprising a device that coversat least a portion of a patient's skin, wherein the device has an innersurface and an outer surface, wherein the inner surface is designed tobe in contact with the patient's skin, wherein the inner surface of thedevice comprises a multi-ply knit fabric having an upper and lowersurface and a length and width, wherein the fabric comprises: a firstknit ply comprising a plurality of first yarns, wherein the first knitply forms the upper surface of the fabric; a second knit ply comprisinga plurality of polytetrafluoroethylene (PTFE) yarns, wherein the PTFEyarns have a density of about 2 to 2.3 g/cm³, a transmission in the IRregion of 8-10 μm at least about 40%, and a thermal conductivity of atleast about 0.2 W/(m·K), wherein the second knit ply forms the lowersurface of the fabric; wherein the first ply and the second plyintegrated through combined portions formed by at least one methodselected from the group consisting of interlacing first yarns among thePTFE yarns of the second knit ply, interlacing PTFE yarns among thefirst yarns of the first knit ply, and interlacing a plurality of thirdyarns among the first yarns of the first knit ply and the PTFE yarns ofthe second knit ply; and, a composition comprising at least one silverion-containing compound on at least the upper surface of the multi-plyknit fabric; wherein the multi-ply knit fabric is positioned such thatthe lower surface of the multi-layer knit fabric is adjacent thepatient's skin.
 2. The medical device of claim 1, wherein the PTFE yarnshave a generally rectangular cross-sectional shape.
 3. The medicaldevice of claim 1, wherein the fabric comprises less than about 75% byweight PTFE yarns.
 4. The medical device of claim 1, wherein the fabriccomprises less than about 50% by weight PTFE yarns.
 5. The medicaldevice of claim 1, wherein the second knit ply comprises at least about90% by weight PTFE yarns.
 6. The medical device of claim 1, wherein thePTFE yarns comprise a density of about 2.15 to 2.25 g/cm³.
 7. Themedical device of claim 1, wherein the PTFE yarns comprise atransmission in the IR region of 8-10 μm at least about 60%.
 8. Themedical device of claim 1, wherein the PTFE yarns comprise a thermalconductivity of at least about 0.23 W/(m·K).
 9. The medical device ofclaim 1, wherein the rectangular cross-sectional shape of the PTFE yarnshas a width to height ratio of between about 20:1 to 100:1.
 10. Themedical device of claim 1, wherein the lower surface of the fabric has asurface roughness of less than about 500 μm.
 11. The medical device ofclaim 1, wherein the multi-ply knit fabric comprises a composition on atleast the upper surface of the multi-ply knit fabric, wherein thecomposition comprises at least one silver ion-containing compound. 12.The medical device of claim 11, wherein the at least one silverion-containing compound is selected from the group consisting of silverion exchange materials, silver particles, silver salts, silver glass,and mixtures thereof.
 13. The medical device of claim 12, wherein thesilver ion exchange material is selected from the group consisting ofsilver zirconium phosphate, silver calcium phosphate, silver zeolite,and mixtures thereof.
 14. The medical device of claim 12, wherein thesilver ion exchange material is silver zirconium phosphate.
 15. Themedical device of claim 1, wherein the composition further comprises abinding agent selected from the group consisting of polyurethanebinders, acrylic binders, and mixtures thereof.
 16. The medical deviceof 15, wherein the binding agent is a polyurethane-based material. 17.The medical device of claim 1, wherein the medical device comprises acast.
 18. The medical device of claim 1, wherein the medical devicecomprises a compression device.
 19. The medical device of claim 1,wherein the medical device comprises a decompression device.